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Data Administration and Database Administration University of California, Berkeley School of Information Management and Systems SIMS 257: Database Management 10/17/2000 Database Management -- R. Larson Mid-Term Assignment #5 • See WWW site: – http://sims.berkeley.edu/courses/is257/f00/index.html • Report on personal database including: – – – – – – 10/17/2000 Database description Data Dictionary Relationships Diagram Sample queries and results Sample forms Sample reports Database Management -- R. Larson Review • Web enabled database systems 10/17/2000 Database Management -- R. Larson Why Use a Database System? • Database systems have concentrated on providing solutions for many issues in scaling up Web applications – – – – – Performance Scalability Maintenance Data Integrity Transaction support • While systems differ in their support, most offer some support for all of these. 10/17/2000 Database Management -- R. Larson Dynamic Web Applications 2 Web Server Internet Files CGI DBMS Server database database database 10/17/2000 Clients Database Management -- R. Larson Server Interfaces SQL HTML DHTML Web Server JavaScript Native DB Interfaces Database Web DB CGI App ODBC Web Server API’s ColdFusion Native DB interfaces JDBC PhP Perl Web Application Server Adapted from John P Ashenfelter, Choosing a Database for Your Web Site 10/17/2000 Java ASP Database Management -- R. Larson What Database systems are available? • Choices depend on: – Size (current and projected) of the application – Hardware and OS Platforms to be used in the application – Features required • E.g.: SQL? Upgrade path? Full-text indexing? Attribute size limitations? Locking protocols? Direct Web Server access? Security? – – – – 10/17/2000 Staff support for DBA, etc. Programming support (or lack thereof) Cost/complexity of administration Budget Database Management -- R. Larson Desktop Database Systems System (producer)Platform SQL ODBC Scaling Access (Microsoft) FoxPro (Microsoft) FileMaker (FileMaker) Excel (Microsoft) Files (owner) Yes Yes No No No Yes Yes No Yes No SQL Server ~$200 SQL Server ~$200 FileMaker Server ~$200 Convert to Access~$200 Import into DB ? Windows Windows, Windows, Windows, Windows, Mac Mac Mac Mac Price • Individuals or very small enterprises can create DBMS-enabled Web applications relatively inexpensively • Some systems will require an application server (such as ColdFusion) to provide the access path between the Web server and the DBMS 10/17/2000 Database Management -- R. Larson Enterprise Database Systems System Platform SQL ODBC JDBC Web? SQL-Server (Microsoft) Oracle Internet Platform Informix Internet Foundation.2000 Sybase Adaptive Server DB2 (IBM) WIndowsNT -2000 Unix, Linux, NT Unix, Linux, NT Unix, Linux, NT IBM,Unix, Linux, NT Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes (IIS) Yes Yes Yes Yes? • Enterprise servers are powerful and available in many different configurations • They also tend to be VERY expensive • Pricing is usually based on users, or CPU’s 10/17/2000 Database Management -- R. Larson Free Database Servers System Platform SQL ODBC JDBC Web? mSQL Unix, Linux Yes MySQL Unix, Linux, NT Yes PostgreSQL Unix, Linux, NT Yes Yes Yes Yes No(?) No(?) Yes No? No? No? • System is free, but there is also no help line. • Include many of the features of Enterprise systems, but tend to be lighter weight • Versions may vary in support for different systems • Open Source -- So programmers can add features 10/17/2000 Database Management -- R. Larson Embedded Database Servers System Platform SQL ODBCJDBC Web? Sleepycat DB Unix, Linux, Win No Solid Unix, Linux, Win Yes No Yes Java API No? Yes Yes • May require programming experience to install • Tend to be fast and economical in space requirements 10/17/2000 Database Management -- R. Larson Database Security • Different systems vary in security support: – Views or restricted subschemas – Authorization rules to identify users and the actions they can perform – User-defined procedures (and rule systems) to define additional constraints or limitations in using the database – Encryption to encode sensitive data – Authentication schemes to positively identify a person attempting to gain access to the database 10/17/2000 Database Management -- R. Larson Web Application Server Software • • • • ColdFusion PHP ASP All of the are server-side scripting languages that embed code in HTML pages 10/17/2000 Database Management -- R. Larson ColdFusion • Started as CGI – Drawback, as noted above, is that the entire system is run for each cgi invocation • Split into cooperating components – NT service -- runs constantly – Server modules for 4 main Web Server API (glue that binds web server to ColdFusion service) {Apache, ISAPI, NSAPI, WSAPI} – Special CGI scripts for other servers 10/17/2000 Database Management -- R. Larson What ColdFusion is Good for • Putting up databases onto the Web • Handling dynamic databases (Frequent updates, etc) • Making databases searchable and updateable by users. 10/17/2000 Database Management -- R. Larson Requirements • Unix or NT systems • Install as SuperUser • Databases must be defined via “data source names (DSNs) by administrator 10/17/2000 Database Management -- R. Larson Requirements and Set Up • Field names should be devoid of spaces. Use the underscore character, like new_items instead of "new items." • Use key fields. Greatly reduces search time. • Check permissions on the individual tables in your database and make sure that they have read-access for the username your Web server uses to log in. • If your fields include large blocks of text, you'll want to include basic HTML coding within the text itself, including boldface, italics, and paragraph markers. 10/17/2000 Database Management -- R. Larson Templates cont. • • • • • • • • • • • • <HEAD> <TITLE>Contents of My Shopping Cart</TITLE> </HEAD> <BODY> <H1>Contents of My Shopping Cart</H1> <CFOUTPUT QUERY= ”cart"> <B>#Item#</B> <BR> #Date_of_item# <BR> $#Price# <P> </CFOUTPUT> </BODY> </HTML> 10/17/2000 Database Management -- R. Larson CFML ColdFusion Markup Language • Read data from and update data to databases and tables • Create dynamic data-driven pages • Perform conditional processing • Populate forms with live data • Process form submissions • Generate and retrieve email messages • Perform HTTP and FTP function • Perform credit card verification and authorization • Read and write client-side cookies 10/17/2000 Database Management -- R. Larson PHP • PHP is an Open Source Software project with many programmers working on the code. – Commonly paired with MySQL, another OSS project – Free – Both Windows and Unix support • Estimated that more than 250,000 web sites use PHP as an Apache Module. 10/17/2000 Database Management -- R. Larson PHP Syntax • Similar to ASP <HTML><BODY> <?php $myvar = “Hello World”; echo $myvar ; ?> </BODY></HTML> • Includes most programming structures (Loops, functions, Arrays, etc.) • Loads HTML form variables so that they are addressable by name 10/17/2000 Database Management -- R. Larson Combined with MySQL • DBMS interface appears as a set of functions: <HTML><BODY> <?php $db = mysql_connect(“localhost”, “root”); mysql_select_db(“mydb”,$db); $result = mysql_query(“SELECT * FROM employees”, $db); Printf(“First Name: %s <br>\n”, mysql_result($result, 0 “first”); Printf(“Last Name: %s <br>\n”, mysql_result($result, 0 “last”); ?></BODY></HTML> 10/17/2000 Database Management -- R. Larson ASP – Active Server Pages • Another server-side scripting language • From Microsoft using Visual Basic as the Language model (VBScript), though Javascript (actually MS Jscript) is also supported • Works with Microsoft IIS and gives access to ODBC databases 10/17/2000 Database Management -- R. Larson ASP Syntax <% SQL="SELECT last, first FROM employees ORDER BY last" set conn = server.createobject("ADODB.Connection") conn.open “employee" set people=conn.execute(SQL) %> <% do while not people.eof set resultline=people(0) & “, “ & people(1) & “<BR>” Response.Write(resultline) people.movenext loop%> <% people.close %> 10/17/2000 Database Management -- R. Larson Conclusions • Database technology is a required component for large-scale dynamic Web sites, especially E-Commerce sites • Web databases cover most of the needs of dynamic sites (except for text search) • Many solutions and systems are available for web-enabled databases 10/17/2000 Database Management -- R. Larson Today • Data Administration • Database Administration 10/17/2000 Database Management -- R. Larson Terms and Concepts • Data Administration – Responsibility for the overall management of data resources within an organization • Database Administration – Responsibility for physical database design and technical issues in database management • Data Steward – Responsibility for some subset of the organization’s data, and all of the interactions (applications, user access, etc.) for that data 10/17/2000 Database Management -- R. Larson Terms and Concepts • DA – Data adminstrator - person responsible for the Data Administration function in an organization – Sometimes may be the CIO -- Chief Information Officer • DBA – Database Administrator - person responsible for the Database Administration Function 10/17/2000 Database Management -- R. Larson Database System Life Cycle Database Planning Database Analysis Growth & Change Operation & Maintenance Database Design Database Implementation 10/17/2000 Database Management -- R. Larson Note: this is a different version of this life cycle than discussed previously Database Planning • Development of a strategic plan for database development that supports the overall organization’s business plan. • DA supports top management in development of this plan. • The result of this stage is an enterprise data model. 10/17/2000 Database Management -- R. Larson Database Planning: DA & DBA functions • • • • • Develop corporate database strategy (DA) Develop enterprise model (DA) Develop cost/benefit models (DA) Design database environment (DA) Develop data administration plan (DA) 10/17/2000 Database Management -- R. Larson Database Analysis • This is the process (discussed previously) of identifying data entities currently used by the organization, precisely defining those entities and their relationships, and documenting the results in a form that can support the follow-on design phase. • Must also identify new data elements or changes to data elements that will be required in the future. • The result of this phase is the Conceptual Data Model -- usually represented as an ER diagram. 10/17/2000 Database Management -- R. Larson Database Analysis: DA & DBA functions • • • • Define and model data requirements (DA) Define and model business rules (DA) Define operational requirements (DA) Maintain corporate Data Dictionary (DA) 10/17/2000 Database Management -- R. Larson Database Design • Purpose of the design phase is the development of the logical database design that will serve the needs of the organization and the physical design implementing the logical design. • In relational systems the outcome is normalized relations, and the data definition for a particular database systems (including indexes, etc.) 10/17/2000 Database Management -- R. Larson Design 2: Physical Creation • Development of the Physical Model of the Database – data formats and types – determination of indexes, etc. • Load a prototype database and test • Determine and implement security, privacy and access controls • Determine and implement integrity constraints 10/17/2000 Database Management -- R. Larson Database Design: DA &DBA functions • Perform logical database design (DA) • Design external models (subschemas) (DBA) • Design internal model (Physical design) (DBA) • Design integrity controls (DBA) 10/17/2000 Database Management -- R. Larson Database Implementation • Database design gives you an empty database • Load data into the database structure • Convert existing data sets and applications to use the new database – May need programs, conversion utilities to convert old data to new formats. • Outcome is the actual database with its data 10/17/2000 Database Management -- R. Larson Database Implementation DA & DBA functions • • • • • Specify database access policies (DA & DBA) Establish Security controls (DBA) Supervise Database loading (DBA) Specify test procedures (DBA) Develop application programming standards (DBA) • Establish procedures for backup and recovery (DBA) • Conduct User training (DA & DBA) 10/17/2000 Database Management -- R. Larson Operation and Maintenance 1: Operations • Users are responsible for updating the database, DA and DBA are responsible for developing procedures that ensure the integrity and security of the database during the update process. • Specific responsibility for data collection, editing and verification must be assigned • Quality assurance must be practiced to protect and audit the database quality. 10/17/2000 Database Management -- R. Larson Operation and Maintenance 2: Maintenance • The ongoing process of updating the database to keep it current – – – – adding new records deleting obsolete records changing data values in particular records modifying relation structures (e.g. adding new fields) • Privacy, security, access control must be in place. • Recovery and Backup procedures must be established and used 10/17/2000 Database Management -- R. Larson Operation and Maintenance: DA & DBA functions • • • • Monitor database performance (DBA) Tune and reorganize databases (DBA) Enforce standards and procedures (DBA) Support users (DA & DBA) 10/17/2000 Database Management -- R. Larson Growth & Change • Change is a way of life – Applications, data requirements, reports, etc. will all change as new needs and requirements are found – The Database and applications and will need to be modified to meet the needs of changes to the organization and the environment. – Database performance should be monitored to maintain a high level of system performance. 10/17/2000 Database Management -- R. Larson Growth & Change: DA & DBA functions • Implement change control procedures (DA & DBA) • Plan for growth and change (DA & DBA) • Evaluate new technology (DA & DBA) 10/17/2000 Database Management -- R. Larson Issues/functions in Database Administration • Planning and Design (we have already looked at theses processes in detail) • Data Integrity • Backup and Recovery • Security Management 10/17/2000 Database Management -- R. Larson Data Integrity • Intrarecord integrity (enforcing constraints on contents of fields, etc.) • Referential Integrity (enforcing the validity of references between records in the database) • Concurrency control (ensuring the validity of database updates in a shared multiuser environment). 10/17/2000 Database Management -- R. Larson No Concurrency Control: Lost updates John • Read account balance (balance = $1000) • Withdraw $200 (balance = $800) • Write account balance (balance = $800) 10/17/2000 Marsha • Read account balance (balance = $1000) • Withdraw $300 (balance = $700) • Write account balance (balance = $700) Database Management -- R. Larson ERROR! Concurrency Control: Locking • Locking levels – – – – – Database Table Block or page Record Field • Types – Shared (S locks) – Exclusive (X locks) 10/17/2000 Database Management -- R. Larson Concurrency Control: Updates with X locking John • Lock account balance • Read account balance (balance = $1000) • Withdraw $200 (balance = $800) • Write account balance (balance = $800) • Unlock account balance 10/17/2000 Marsha • Read account balance (DENIED) • Lock account balance • Read account balance (balance = $800) • etc... Database Management -- R. Larson Concurrency Control: Deadlocks John • Place S lock • Read account balance (balance = $1000) Marsha • Place S lock • Read account balance (balance = $1000) • Request X lock (denied) • wait ... • Request X lock (denied) • wait... 10/17/2000 Database Management -- R. Larson Deadlock! Concurrency Control • Avoiding deadlocks by maintaining tables of potential deadlocks and “backing out” one side of a conflicting transaction. 10/17/2000 Database Management -- R. Larson Database Security • Views or restricted subschemas • Authorization rules to identify users and the actions they can perform • User-defined procedures (and rule systems) to define additional constraints or limitations in using the database • Encryption to encode sensitive data • Authentication schemes to positively identify a person attempting to gain access to the database 10/17/2000 Database Management -- R. Larson Views • A subset of the database presented to some set of users. – SQL: CREATE VIEW viewname AS SELECT field1, field2, field3,…, FROM table1, table2 WHERE <where clause>; – Note: “queries” in Access function as views. 10/17/2000 Database Management -- R. Larson Authorization Rules • Most current DBMS permit the DBA to define “access permissions” on a table by table basis (at least) using the GRANT and REVOKE SQL commands. • Some systems permit finer grained authorization (most use GRANT and REVOKE on variant views. 10/17/2000 Database Management -- R. Larson Database Backup and Recovery • • • • Backup Journaling (audit trail) Checkpoint facility Recovery manager 10/17/2000 Database Management -- R. Larson